1. Field
The following description relates to technology for a food search service, and more particularly, to an apparatus and method for a food search service which can extract and refine candidate regions likely to be recognized as food regions in a food image, and also can locate a position of food in the image.
2. Description of Related Art
Food search services provide users with a diversity of information found about food, such as taste, nutritional data, a restaurant location, a recipe, and the like. Recently, web portal operators have been actively providing information search services related to food by analyzing food images that they have collected in their database. Examples of such food search services include “Im2Calrories” of Google and “View Restaurants (beta)” of Naver, a South Korean Web portal.
An image may portray one dish placed at the center of a table, multiple dishes on the table, or a food tray. Therefore, in order to detect all foods in an image, an art is need that can find the candidate region, and thus extract and classify multiple food regions in a specific area.
In this regard, a method has been suggested which can detect candidate regions using a deformable part model (DPM), a circle detector, and region segmentation, and recognize food items by applying various visual feature extraction methods, including a color histogram and scale invariant feature transform (SIFT), to the candidate regions. However, in this method, boundaries between food regions are not distinguished during the detection of candidate regions, and hence the recognition rate is very low and not many kinds of food can be thus detected.
In addition, in order to detect many kinds of candidate regions, a method has been suggested that normalizes image gradients and extracts multiple object regions by 8×8-binary feature extraction. However, because the object detection suggested by this method is not specialized for the purpose of food recognition, a food region ratio and similarity between object regions are not taken into account, and so it is difficult to achieve reliable search results.
Also, in order to estimate calories of a meal on a food tray, a method has been proposed that recognizes one or more food items of said meal using information about foods' colors and textures. This method includes processes of classification and segmentation of a food image, but does not describe extraction of a candidate region or its position information for identifying a food region.